If you're based outside of Poland, you’re liable from your first sale. For businesses based in Poland, sales exceeding PLN 200,000 (~$54,000) are liable for sales tax.
Yes. You owe tax for the sale of cloud software subscriptions to customers in Poland.
Yes. You owe tax for the sale of software downloads to customers in Poland.
Yes. You owe tax for the sale of eBooks to customers in Poland.
Yes. You owe tax for the sale of digital downloads to customers in Poland.